ISLSCP II -- Land/Water Masks

ISLSCP Initiative II

Related Pages
ISLSCP Initiative II Home General Data Overview Ancillary Data Overview

Ancillary Data

Land/Water Masks

This data set contains the ISLSCP II fixed land/water masks and percentages of land or water in each cell. These data were produced from a 1km land/water mask compiled at the Jet Propulsion Laboratory (JPL) in support of NASA's Earth Observing System. It also contains a land outline overlay created from the land/water mask files.
The original 1km mask was produced at JPL from the Digital Chart of the World and the World Vector Shoreline data bases. These data were aggregated from their original 1km spatial resolution to 1 degree (1d), 1/2 degree (hd), and 1/4 degree (hd). Through the aggregation process the percentages of water and/or land in the coarser cell were also calculated. The binary land/water masks (0=Water; 1=Land) were produced from cells containing 50% or greater amounts of water.
There is an additional "binary" land/water product, created from the original maps to help process other data sets. It was decided to include this because it was useful. This product has -99 for water and -88 for land, at all three resolutions.

Data Provider: JPL

Click to access data
Data Files
(ISLSCP II Disc #1)
Data Set
Documentation
Image Viewing
Tutorial

File Information

The files have been compressed using the PKZip program. Each file contains ASCII text at 1 degree (360 values per line, and 180 lines, labeled "1d"), 0.5 degrees (720 values per line, and 360 lines, labeled as "hd"), and 0.25 degrees (1440 values per line, and 720 lines, labeled as "qd"). Each line is terminated by a newline character. Each line is terminated by a newline character. The data are structured so that the upperleft corner of the first pixel is located at 90 North latitude and 180 West longitude. The following files are available:

Standard Land/Water Masks
Contained in the file "land_water_masks_xdeg.zip"

o land_water_mask_xx.asc: Global gridded binary land/water masks, with values of 0 and 1 (Water=0; Land=1). xx is the resolution as above.

o land_percent_xx.asc: Percentage of original 30 arcsecond land cells located within coarser resolution cells, from 0 to 100. xx is the resolution as above. These files are used to construct the binary land/water masks.

o water_percent_xx.asc: Percentage of original 30 arcsecond water cells (including inland water) located within coarser resolution cells, from 0 to 100. xx is the resolution as above. These files are used to construct the binary land/water masks.

Special Land/Water Masks (land=-88, water=-99)
Contained in the file "land_water_masks-99_xdeg.zip"

o land_water_mask-99_xx.asc: Global gridded binary land/water masks, with values of -88 and -99 (Water=-99; Land=-88). xx is the resolution as above. These files were used as the bases for several derived map products (point data was plotted on top of these maps), so they are included here as a baseline comparison product.

Special Land/Ocean Masks (no inland water bodies)
Contained in the file "land_ocean_masks_xdeg.zip"

o land_ocean_mask_xx.asc: Global gridded binary land/ocean masks, with values of 0 and 1 (Ocean=0; Land=1). xx is the resolution as above. NOTE that these are masks of only land and oceans and do not contain inland water bodies.

o land_percent2_xx.asc: Percentage of original 30 arcsecond land cells located within coarser resolution cells, from 0 to 100. xx is the resolution as above. These files are used to construct the binary land/ocean masks. NOTE that these files are different from the land_percent_xx.asc files because inland water bodies are not considered.

o ocean_percent2_xx.asc: Percentage of original 30 arcsecond sea or ocean cells located within coarser resolution cells, from 0 to 100. xx is the resolution as above. These files are used to construct the binary land/ocean masks. NOTE that these files do not contain inland water bodies and are different from the "water_percent_xx.asc" files.

Special Inland Water Masks (only inland water bodies)
Contained in the file "inland_water_masks_xdeg.zip"

o inland_water_mask_xx.asc: Global gridded binary inland water bodies masks, with values of 0 and 1 (Inland Water=1; Other=0). xx is the resolution as above. NOTE that these are masks of only inland water bodies, no land or oceans are included.

o other_percent_xx.asc: Percentage of original 30 arcsecond non-inland water cells (i.e. land and oceans) located within coarser resolution cells, from 0 to 100. xx is the resolution as above. These files are used to construct the binary inland water bodies masks.

o inland_water_percent_xx.asc: Percentage of original 30 arcsecond inland water cells located within coarser resolution cells, from 0 to 100. xx is the resolution as above. These files are used to construct the binary inland water bodies masks.

Related Pages:
ISLSCP Initiative II Home
General Data Overview
Ancillary Data Overview
Land/Water Masks

Revision Date: July 1, 2003

Standard Land/Water Masks Contained in the file "land_water_masks_xdeg.zip"
o	land_water_mask_xx.asc: Global gridded binary land/water masks, with values of 0 and 1 (Water=0; Land=1). xx is the resolution as above.
o	land_percent_xx.asc: Percentage of original 30 arcsecond land cells located within coarser resolution cells, from 0 to 100. xx is the resolution as above. These files are used to construct the binary land/water masks.
o	water_percent_xx.asc: Percentage of original 30 arcsecond water cells (including inland water) located within coarser resolution cells, from 0 to 100. xx is the resolution as above. These files are used to construct the binary land/water masks.

Special Land/Water Masks (land=-88, water=-99) Contained in the file "land_water_masks-99_xdeg.zip"
o	land_water_mask-99_xx.asc: Global gridded binary land/water masks, with values of -88 and -99 (Water=-99; Land=-88). xx is the resolution as above. These files were used as the bases for several derived map products (point data was plotted on top of these maps), so they are included here as a baseline comparison product.

Special Land/Ocean Masks (no inland water bodies) Contained in the file "land_ocean_masks_xdeg.zip"
o	land_ocean_mask_xx.asc: Global gridded binary land/ocean masks, with values of 0 and 1 (Ocean=0; Land=1). xx is the resolution as above. NOTE that these are masks of only land and oceans and do not contain inland water bodies.
o	land_percent2_xx.asc: Percentage of original 30 arcsecond land cells located within coarser resolution cells, from 0 to 100. xx is the resolution as above. These files are used to construct the binary land/ocean masks. NOTE that these files are different from the land_percent_xx.asc files because inland water bodies are not considered.
o	ocean_percent2_xx.asc: Percentage of original 30 arcsecond sea or ocean cells located within coarser resolution cells, from 0 to 100. xx is the resolution as above. These files are used to construct the binary land/ocean masks. NOTE that these files do not contain inland water bodies and are different from the "water_percent_xx.asc" files.

Special Inland Water Masks (only inland water bodies) Contained in the file "inland_water_masks_xdeg.zip"
o	inland_water_mask_xx.asc: Global gridded binary inland water bodies masks, with values of 0 and 1 (Inland Water=1; Other=0). xx is the resolution as above. NOTE that these are masks of only inland water bodies, no land or oceans are included.
o	other_percent_xx.asc: Percentage of original 30 arcsecond non-inland water cells (i.e. land and oceans) located within coarser resolution cells, from 0 to 100. xx is the resolution as above. These files are used to construct the binary inland water bodies masks.
o	inland_water_percent_xx.asc: Percentage of original 30 arcsecond inland water cells located within coarser resolution cells, from 0 to 100. xx is the resolution as above. These files are used to construct the binary inland water bodies masks.